A system for automatically adjusting directions of optical axes of front lights for vehicles is disclosed in U.S. Pat. No. 6,671,640 (JP-A-2002-178829). This system is for changing the response in the swivel control relying upon the angular velocity (change speed) of the steering angle of a steering wheel as a steering operation parameter at the time of swivel-controlling the directions of optical axes of the front lights in the right-and-left direction depending upon the steering of the steering wheel.
This system varies the response by switching filters. However, a sharp swivel control based on a frequent switching of the filters gives discomfort to drivers. Further, when the steering wheel is slowly turned from the neutral position, the swivel control starts in a delayed manner giving discomfort to the driver.